Collaborative Research: Symbiosis as a fulcrum in a rapidly warming world

合作研究：共生作为快速变暖世界的支点

• 批准号: 2240392
• 负责人: Kerry Oliver
• 金额: $ 68.62万
• 依托单位: University of Georgia Research Foundation Inc
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-15 至 2027-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2240392&HistoricalAwards=false
• 关键词: Collaborative; Research; Symbiosis; fulcrum; rapidly

Climate change is creating unprecedented challenges for Earth’s inhabitants. It is critical to understand how rising temperatures affect the diversity and distributions of organisms. However, predicting organismal responses to climate change is difficult, because species interactions are impacted differently than individual species. Moreover, these predictions are further complicated because species interactions often involve ‘hidden’ microbes called symbionts, which appear especially vulnerable to climate change. This is exemplified by the photosynthesizing symbionts of marine corals, which are expelled during ocean warming. Less is known about climate impacts on symbiont-mediated species interactions in terrestrial systems. Unique opportunities to study this phenomenon occur using tractable aphid models with their well-characterized protective symbioses. Aphids are plant-feeding insects and important agricultural pests, which carry bacterial symbionts that protect them against pathogens and parasites. Prior work showed that most strains of a widespread anti-parasite symbiosis failed to protect aphids at warmer temperatures. But other strains of this symbiont, and from a second non-essential symbiont species, provided aphids with tolerance to high temperatures in the absence of parasites– plausibly by rescuing a third symbiont species required for aphid survival. Combining biological experiments with molecular biology, microscopy, genomics and gene expression studies, the PIs will study mechanisms of temperature-mediated symbiont failure and, conversely, the potential for symbiont-mediated climate resilience. Insects are the most diverse animal group, and most are symbiotic, so findings from aphids readily generalize to most terrestrial animals. This award supports the training and professional development of high school, undergraduate, graduate researchers, and includes community outreach events. Predicting organismal responses to climate change is difficult because species interactions are impacted differently than individual species. A further complication is that interactions among multicellular eukaryotes are often mediated by microbial partners, which appear especially vulnerable to thermal stress. Climate impacts on microbe-mediated species interactions will be investigated using a highly-tractable aphid model system with defensive symbioses that have been well-characterized at genotypic and phenotypic levels. Prior work showed that most strains of a widespread anti-parasitoid symbiont, Hamiltonella, fail to protect aphids at warmer temperatures. Using common strains derived from natural populations, cage experiments will test hypotheses that 1) fluctuating temperatures maintain thermally-relevant genetic variation in Hamiltonella, while 2) monolithic exposure to hot temperatures without parasitoids selects for strains conferring thermal tolerance, and 3) challenge with both warm temperatures and parasitoids selects for strains providing thermally-robust protection. Additional assays will define the upper limits of Hamiltonella function, and whether another symbiont, Serratia, replaces Hamiltonella in the hottest locales. To understand mechanisms of symbiont failure and resilience, relevant genomes will be sequenced coupled with assays examining symbiont titers in response to thermal stress, heat lability of toxins, and whether thermal tolerance occurs via rescue of the obligate nutritional symbiont Buchnera. This research enhances understanding of climate impacts on the ubiquitous heritable symbioses of insects, with implications for the many beneficial services provided, and threats to human health and agriculture posed.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

气候变化正在给地球上的居民带来前所未有的挑战。了解气温上升如何影响生物的多样性和分布是至关重要的。然而，预测生物对气候变化的反应是困难的，因为物种之间的相互作用受到的影响不同于单个物种。此外，这些预测更加复杂，因为物种间的相互作用往往涉及被称为共生体的“隐藏”微生物，它们似乎特别容易受到气候变化的影响。海洋珊瑚的光合作用共生体就是一个例证，它们在海洋变暖期间被驱逐出去。关于气候对陆地系统中共生体介导的物种相互作用的影响，人们知之甚少。研究这一现象的独特机会是利用易驯化的、具有良好特征的保护性共生体的蚜虫模型。蚜虫是以植物为食的昆虫和重要的农业害虫，它们携带细菌共生体，保护它们免受病原体和寄生虫的侵袭。先前的工作表明，广泛存在的抗寄生虫共生的大多数菌株在较温暖的温度下无法保护蚜虫。但是，这种共生菌的其他菌株，以及来自第二个非必需共生体物种的菌株，为蚜虫提供了在没有寄生虫的情况下对高温的耐受性--这似乎是通过拯救第三个共生体物种来拯救蚜虫生存所需的。将生物学实验与分子生物学、显微镜、基因组学和基因表达研究相结合，PI将研究温度介导的共生体失败的机制，反过来，研究共生体介导的气候适应能力的可能性。昆虫是最多样化的动物群体，而且大多数是共生的，所以从蚜虫身上发现的结果很容易推广到大多数陆地动物。该奖项支持高中、本科和研究生研究人员的培训和专业发展，并包括社区外展活动。预测生物对气候变化的反应是困难的，因为物种间的相互作用受到的影响不同于单个物种。更复杂的是，多细胞真核生物之间的相互作用往往是由微生物伙伴介导的，而微生物伙伴似乎特别容易受到热应激的影响。气候对微生物介导的物种相互作用的影响将使用一个高度易驯化的具有防御性共生的蚜虫模型系统进行研究，这些共生已经在基因和表型水平上得到了很好的表征。先前的工作表明，一种广泛存在的抗寄生性共生菌哈密尔顿菌的大多数菌株在较温暖的温度下无法保护蚜虫。使用来自自然种群的常见菌株，笼式实验将检验以下假设：1)波动的温度维持哈密尔顿菌与温度相关的遗传变异，2)整体暴露在高温而不带寄生虫的环境中，选择具有耐热性的菌株，以及3)同时挑战温暖温度和寄生虫，选择提供耐热保护的菌株。其他化验将确定哈密尔顿氏菌功能的上限，以及在最热的地区，另一种共生菌沙雷氏菌是否会取代汉密尔顿氏菌。为了了解共生菌失败和恢复的机制，将对相关基因组进行测序，并结合检测共生菌滴度对热应激的响应、毒素的热不稳定以及是否通过抢救专有营养共生菌Buchnera而发生热耐受。这项研究加强了对气候对昆虫普遍存在的可遗传共生环境的影响的理解，以及对所提供的许多有益服务的影响，以及对人类健康和农业的威胁。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。